One major contrast between natural and synthetic macromolecules is that the latter usually lack well-defined high order structures. Following Nature's strategy, we are introducing weak molecular forces into synthetic macromolecules to guide the formation of high order structures. In one example, using spider silk and beta-amyloid fibers as models, we have created synthetic polymers that fold into extensive beta-sheets and self assemble into nanofibrils. In another example, by mimicking skeletal muscle protein titin, we have designed multidomain polymers having tandem arrays of modules folded by well-defined hydrogen bonds. Drawing various inspirations from Nature, we are programming covalent and subtle non-covalent molecular forces to create a plethora of biomimetic materials showing dynamic, responsive, shape-memory, and self-healing properties.

To elucidate the molecular origin for material properties and build fundamental structure-property correlations, we are also investigating their materials properties at various length scales: from single molecule, nanoscopic, microscopic, finally to bulk level. As shown below, we measure the single molecule force spectroscopy (SMFS) of individual polymer chains using Atomic Force Microscopy (AFM), which provides critical nanomechanical information that cannot be obtained from conventional ensemble measurements. Ultimately, insight into the relation between the single-molecule properties of materials and their performance at macroscopic level will guide us to rationally design advanced materials with desired properties.